Endovascular prosthesis

ABSTRACT

A endovascular prosthesis for implantation in a body passageway. The prosthesis comprises a tubular wall which is: (i) movable between a first longitudinal length and a second longitudinally length, and (ii) radially expandible for implantation of the prosthesis in the body passageway. In one embodiment, the tubular wall has a longitudinally length which is variable by an “accordian”-like action. In another embodiment, the tubular wall has a longitudinally length which is variable by an “telescoping”-like action. The longitudinal length of the tubular wall may be varied in vivo to optimize deployment of the endovascular prosthesis.

TECHNICAL FIELD

[0001] In one of its aspects, the present invention relates to anendovascular prosthesis. In another of its aspects, the presentinvention relates to a method of treating an aortic disease condition ina patient.

BACKGROUND ART

[0002] Stents are generally known. Indeed, the term “stent” has beenused interchangeably with terms such as “intraluminal vascular graft”and “expandable prosthesis”. As used throughout this specification theterm “stent” is intended to have a broad meaning and encompasses anyexpandable prosthetic device for implantation in a body passageway(e.g., a lumen or artery).

[0003] In the past ten years, the use of stents has attracted anincreasing amount of attention due the potential of these devices to beused in certain cases, as an alternative to surgery. Generally, a stentis used to obtain and maintain the patency of the body passageway whilemaintaining the integrity of the passageway. As used in thisspecification, the term “body passageway” is intended to have a broadmeaning and encompasses any duct (e.g., natural or iatrogenic) withinthe human body and can include a member selected from the groupcomprising: blood vessels, respiratory ducts, gastrointestinal ducts andthe like.

[0004] Stent development has evolved to the point where the vastmajority of currently available stents rely on controlled plasticdeformation of the entire structure of the stent at the target bodypassageway so that only sufficient force to maintain the patency of thebody passageway is applied during expansion of the stent.

[0005] Generally, in many of these systems, a stent, in association witha balloon, is delivered to the target area of the body passageway by acatheter system. Once the stent has been properly located (for example,for intravascular implantation the target area of the vessel can befilled with a contrast medium to facilitate visualization duringfluoroscopy), the balloon is expanded thereby plastically deforming theentire stricture of the stent so that the latter is urged in placeagainst the body passageway. As indicated above, the amount of forceapplied is at least that necessary to expand the stent (i.e. the appliedthe force exceeds the minimum force above which the stent material willundergo plastic deformation) while maintaining the patency of the bodypassageway. At this point, the balloon is deflated and withdrawn withinthe catheter, and is subsequently removed. Ideally, the stent willremain in place and maintain the target area of the body passagewaysubstantially free of blockage (or narrowing).

[0006] See, for example, any of the following patents:

[0007] U.S. Pat. No. 4,733,665 (Palmaz),

[0008] U.S. Pat. No. 4,739,762 (Palmaz),

[0009] U.S. Pat. No. 4,800,882 (Gianturco),

[0010] U.S. Pat. No. 4,907,336 (Gianturco),

[0011] U.S. Pat. No. 5,035,706 (Gianturco et al.),

[0012] U.S. Pat. No. 5,037,392 (Hillstead),

[0013] U.S. Pat. No. 5,041,126 (Gianturco),

[0014] U.S. Pat. No. 5,102,417 (Palmaz),

[0015] U.S. Pat. No. 5,147,385 (Beck et al.),

[0016] U.S. Pat. No. 5,282,824 (Gianturco),

[0017] U.S. Pat. No. 5,316,023 (Palmaz et al.),

[0018] U.S. Pat. No. 5,755,771 (Penn et al.),

[0019] U.S. Pat. No. 5,906,640 (Penn et al.),

[0020] U.S. Pat. No. 6,217,608 (Penn et al.),

[0021] Canadian patent 1,239,755 (Wallsten), and

[0022] Canadian patent 1,245,527 (Gianturco et al.),

[0023] for a discussion on previous stent designs and deploymentsystems.

[0024] To date, most stent development has focused on the so-calledcoronary stents. While a number of advances in art of coronary stentdevelopment have been made, there is room for improvement.

[0025] One area which has received little or no attention is the area ofendovascular treatment of aortic disease. At this point it is useful toreview diseases of the aorta.

[0026] Aortic diseases contribute to the high overall cardiovascularmortality. Relatively new imaging modalities (e.g., transesophagealechocardiography, magnetic resonance tomography, helical computedtomography, electron beam computed tomography) have been introducedduring the last decade. These new imaging techniques facilitate betterand/or earlier diagnosis of aortic diseases, even in emergencysituations. These new imaging techniques have had an effect on patientmanagement during recent years allowing more rapid diagnosis anddecision making.

[0027] Generally, aortic disease is caused by mechanisms which weakenthe strength of the aortic wall, particularly, the aortic media. Suchwall weakening leads to higher wall stress, which can induce aorticdilatation and aneurysm formation, eventually resulting in aorticdissection or rupture. The various categories of aortic disease aresummarized in FIG. 1.

[0028] Diseases of the aorta are a significant problem in medicine.There are two general approaches: drug treatment and surgery. Drugtreatment is used to lower blood pressure—this approach isdisadvantageous since, at best, it modulates the effect of the diseasewhile still leaving the patient at significant risk. Surgery isdisadvantageous due to the high mortality and morbidity, even in centersof excellence. The increasing age of the population is resulting in anincreased incidence of aortic disease as it is a degenerative disease.Further, aortic stiffness increases with age thereby reducing coronaryand other artery perfusion.

[0029] There are three (3) indications of aortic disease which areregularly of clinical interest: (1) aortic dissection, (2) blunt chesttrauma (with consequential trauma to the aorta), and (3) aorticsclerosis.

[0030] Aortic dissection is known to occur in approximately 15-20cases/1 million inhabitants/year with a mortality of 50% in the firstyear and 5% per hour for the first 5 hours after the onset of symptoms.It results in a splitting of the aortic wall, a bleeding into the wallwith formation of a true and false (new) lumen separated by a flapcalled “intima” with tear or “rupture point”. In patients withinvolvement of the ascending aorta, surgery is performed and drugtreatment preferred in patients with involvement of the descendingaorta. As stated above, despite surgeries mortality is still high. Themain problem is the organ perfusion of the abdomen which results inshock and multiorgan failure. Relatively recent studies havedemonstrated that intramural hemorrhage, intramural hematoma and aorticulcer may be signs of evolving dissections or dissection subtypes.Currently, the various forms of dissection may be classified as follows:

[0031] Class 1 (FIG. 2a): Classical aortic dissection with an intimalflap between true and false lumen;

[0032] Class 2 (FIG. 2b): Medial disruption with formation of intramuralhematoma/hemorrhage;

[0033] Class 3 (FIG. 2c): Discrete/subtle dissection without hematoma,eccentric bulge at tear site;

[0034] Class 4 (FIG. 2d): Plaque rupture leading to aortic ulceration,penetrating aortic atherosclerotic ulcer with surrounding hematoma,usually subadventitial; and

[0035] Class 5 (FIG. 2e): Iatrogenic and traumatic dissection.

[0036] Each of these classes of dissection can be seen in their acuteand chronic stages; chronic dissections are considered to be present ifmore than 14 days have elapsed since the acute event.

[0037] Classic Aortic Dissection (Class 1—FIG. 2a)

[0038] Acute aortic dissection is characterized by the rapid developmentof an intimal flap separating a true lumen and false lumen. Due to thepressure difference the true lumen is usually smaller than the falselumen. Intimal flap tears characterize communicating dissections.However, tears are not always found and non-communicating dissectionsare not uncommon. The dissection can spread from diseased segments ofthe aortic wall in an antegrate or retrograde fashion, involving sidebranches and causing other complications.

[0039] Intramural Hematoma/Hemorrhage (Class 2—FIG. 2b)

[0040] An intramural hematoma is believed to be the initial lesion inthe majority of cases of cystic medial degeneration leading to aorticdissection in which the intimal tear seems to be secondary to precedingintramural dissection. Intramural hematoma may be the result of rupturednormal-appearing vasa vasorum which are not supported by the surroundingaortic media or the result of rupture of diseased vasa vasorum. As adissecting hematoma extends along the aorta the weakened inner wall issubjected to the elongating force of the diastolic recoil. Differencesin elasticity between the aortic fibrous adventitia and the inner moreelastic media may play an additional role.

[0041] In autopsy studies, dissecting aneurysms without tears have beenfound in up to 12% of 311 autopsies. Others studies have reported anincidence of 4% in 505 cases. In a series of sudden deaths, 67% ofpatients with dissections did not have tears. The incidence ofintramural hemorrhage and hematoma in patients with suspected aorticdissection, as observed by various new imaging techniques, seems to bein the range of 10-30%.

[0042] There are two distinct types of intramural hematoma andhemorrhage.

[0043] Type I intramural hematoma and hemorrhage shows a smooth inneraortic lumen, the diameter is usually less than 3.5 cm, and the wallthickness greater than 0.5 cm. Echo free spaces (seenechocardiographically) as a sign of intramural hematoma are found inonly □ of the patients. The mean longitudinal extent of the hematoma isabout 11 cm and the echo free spaces show minimal or no signs of flow.

[0044] Type 11 intramural hematoma and hemorrhage occurs in aorticarteriosclerosis. A rough inner aortic surface with severe aorticsclerosis is characteristic, the aorta is dilated to more than 3.5 cmand calcium deposits are frequently found. Mean wall thickness is 1.3 cmwith a range of from about 0.6 to about 4 cm, and echo free spaces arefound in 70° of the patients studied. The longitudinal extension has asimilar range as in Type I hematoma, usually about 11 cm. Intramuralhemorrhages are more often found in the descending than in the ascendingaorta.

[0045] The fact that intramural hemorrhage and hematoma can lead toaortic dissection has only be demonstrated in follow-up studies. Acuteaortic dissection as a consequence of intramural hemorrhage and hematomadevelops in from about 28% to about 47% of the patients. It isassociated with aortic rupture in from about 21% to about 47%; andregression is seen in about 10% of the patients.

[0046] Subtle-Discrete Aortic Dissection (Class 3—FIG. 2c)

[0047] The structural weakness can either lead to clinically undetecteddisease or minor forms of aortic dissection. Subtle dissection has beendescribed as a partial stellate or linear tear of the vessel wall,covered by thrombus. After the partial tear forms a scar, thisconstellation is called abortive, discrete dissection. Partial rupturesof the inner layer of the aorta allow the blood to enter the alreadydamaged media and thus cause dissection of the aortic wall, eventuallyleading to a second lumen within the wall, to a rupture or healingduring follow-up.

[0048] Plague Rupture/Ulceration (Class 4—FIG. 2d)

[0049] Ulceration of atherosclerotic aortic plaques can lead to aorticdissection or aortic perforation. This was first observed by computedtomography. Innovations in imaging techniques (e.g., intravascularultrasound, spiral computed tomography and magnetic resonance imaging)provide new insight. The ability to diagnose aortic ulceration hasthereby been improved and further affect the descending thoracic aorta,as well as the abdominal aorta, and are usually not associated with anextensive longitudinal propagation or branch vessel compromise.Valvular, pericardial or other vascular complications seem to be rare.The ulcer may penetrate beyond the internal border, often with annipple-like projection with subjacent Type II intramural hematomaformation. The continuous erosion of the atherosclerotic plaque mayeventually violate the internal elastic membrane. False aneurysms,aortic rupture or dissections may occur.

[0050] Aortic sclerosis is normally divided into four grades fromthickening of the intima (Grade I) up to the development of freefloating thrombi (Grade IV) with the danger of embolism. In elderlypatients, the incidence of the Grade IV aortic sclerosis is increasing.This has lead to a significant occurrence of stroke in patients. Thus,if a treatment of aortic sclerosis Grade IV with thrombi free floatingin the aortic lumen could be developed, this would likely obviate ormitigate the consequential occurrence of stroke.

[0051] Currently, there is no reliable treatment approach for aorticsclerosis particularly the Grade IV type. Anticoagulation is a knownapproach, however this treatment must be accepted with the danger ofhemorrhagic strokes, particularly in the older patients Further, thetherapy is very difficult to monitor. Surgery is very complicated andhas a high mortality and morbidity. Currently, surgery is not seen as adesirable alternative to anticoagulation therapy.

[0052] Traumatic/Iatrogenic Aortic Dissection (Class 5—FIG. 2e)

[0053] Blunt chest trauma usually causes dissection of the ascendingaorta and/or the region of the ligamentum Botalli at the aortic isthmus.Iatrogenic dissection of the aorta may rarely occur during heartcatheterization. It is regularly seen following angioplasty of an aorticcoarctation, but can also be observed after cross clamping of the aortaand after the use of intraaortic balloon pumping. Most catheter-induceddissections are retrograde dissections. They will usually decrease insize as the false lumen thromboses. Proximal progression of the coronarydissection into the aortic root may be observed. In blunt chest trauma,the large acceleration of the aorta is leading to an intimal, medial ortranssection of the aorta particularly at the adjunction at the aorticarch and the descending aorta (15-20% of blunt chest trauma cases arerelated to aortic injury). As a consequence of this blunt chest trauma,mediastinal hematoma can occur with abrupt death of the patient. Theblunt chest trauma is known to occur in accidents involving heavymotorcycles and cars, as well as in other chest traumas. The diagnosisis verge difficult but has been improved by transesophagealechocardiography. Typically, the damage to the aorta is limited to asmall portion comprising 3 cm −5 cm of the aorta. Conventionally,surgery was the only treatment to stabilize these patients. A mortalityrate of 90% has been seen if surgery was not timely preformed. Even ifsurgery was timely performed, there is a significant mortality rate.

[0054] Most prior art attempts to improve surgical techniques to treataortic dissection have not be particularly successful.

[0055] It is also worth pointing out that the so-call “stent grafts” arenot well suited for treating diseases of the aorta. Specifically, aconventional stent graft is generally of a fixed longitudinal length.Since the anatomy of each patient is different and the overalllongitudinal length of the aortic or other endoluminal disease conditionis variable, the stent graft should be of a specific or customizedlongitudinal length so as to minimize the occurrence side branchblockage. This is inconvenient and requires inventory stocking of anumber of stent grafts having a variety of different longitudinallengths to have devices on hand for use in most situations.

[0056] Thus, despite the advances made in the art, there is still a needfor an endovascular prosthesis capable obviates or mitigates at leastone of the above-mentioned disadvantages of the prior art. Specificallyit would be desirable to have an endovascular prosthesis whoselongitudinal length could be adjusted in vivo by the physician duringimplanted of the prosthesis.

DISCLOSURE OF THE INDENTION

[0057] It is an object of the present invention to provide a novelendovascular prosthesis which obviates or mitigates at least one of theabove-mentioned disadvantages of the prior art.

[0058] Accordingly, in one of its aspects, the present inventionprovides an endovascular prosthesis for implantation in a bodypassageway, the prosthesis comprising a tubular wall, the tubular wallbeing: (i) movable between a first longitudinal length and a secondlongitudinally length, and (ii) radially expandible for implantation ofthe prosthesis in the body passageway.

[0059] In another of its aspects, the present invention provides anendovascular prosthesis for implantation in a boded passageway, theprosthesis comprising a first tubular wall and a second tubular wall inlongitudinal sliding engagement with one another, the first tubular walland the second tubular wall being radially expandible for implantationof the prosthesis in the body passageway.

[0060] In another of its aspects, the present invention provides amethod for endovascular blocking of an endovascular disease conditionlocated between a first location point and a second location point in atarget body passageway of a patient with an endovascular prosthesiscomprising a first tubular wall and a second tubular wall inlongitudinal sliding engagement with one another the first tubular walland the second tubular wall being radially expandible, the methodcomprising the steps of:

[0061] inserting the prosthesis and a catheter within a body passagewayby catheterization of the body passageway;

[0062] translating the prosthesis and catheter to a target bodypassageway in which the endovascular disease condition is located;

[0063] positioning the distal end of the prosthesis such the distal endof the prosthesis is substantially aligned with the first locationpoint;

[0064] extending the distal end of the prosthesis with respect to thecatheter;

[0065] exerting a radially outward expansive force on the distal end ofthe tubular wall such that the distal end of the tubular wall is urgedagainst the target body passageway;

[0066] fixing a proximal portion of the prosthesis with respect to thecatheter;

[0067] retracting the catheter thereby longitudinally extending theexpansible portion of the tubular wall until the proximal end of theprosthesis is substantially is substantially aligned with the secondlocation point;

[0068] freeing the prosthesis with respect to the catheter;

[0069] retracting the catheter to expose the proximal end of theendovascular prosthesis; and

[0070] exerting a radially outward expansive force on the proximal endof the tubular wall such that the proximal end of the tubular wall isurged against the target body passageway.

[0071] In yet another of its aspects, the present invention provides amethod for endovascular blocking of an endovascular disease conditionlocated between a first location point and a second location point in abody passageway of a patient with endovascular prosthesis comprising atubular wall comprising a distal end and a proximal end, the tubularwall being: (i) movable between a first longitudinal length and a secondlongitudinally length, and (ii) radially expandible for implantation ofthe prosthesis in the body passageway, the method comprising the stepsof:

[0072] disposing the prosthesis in a catheter;

[0073] inserting the prosthesis and catheter within a body passageway bycatheterization of the body passageway;

[0074] translating the prosthesis and catheter to a target bodypassageway in which the endovascular disease condition is located;

[0075] extending the distal end of the prosthesis from the catheter,

[0076] positioning the distal end of the prosthesis such the distal endof the prosthesis is substantially aligned with the first locationpoint;

[0077] exerting a radially outward expansive force on the distal end ofthe tubular wall such that the distal end of the tubular wall is urgedagainst the target body passageway;

[0078] urging the proximal end of the prosthesis against the catheter;

[0079] retracting the catheter thereby longitudinally extending theexpansible portion of the tubular wall until the proximal end of theprosthesis is substantially is substantially aligned with the secondlocation point;

[0080] freeing the proximal end of the prosthesis with respect to thecatheter;

[0081] retracting the catheter to expose the proximal end of theendovascular prosthesis; and

[0082] exerting a radially outboard expansive force oil the proximal endof the tubular wall such that the proximal end of the tubular wall isurged against the target body passageway.

[0083] Generally, the present prosthesis can be advantageously used totreat the indications of aortic disease referred to hereinabove.Specifically, as will be described in more detail hereinbelow, thepresent endovascular prosthesis has a longitudinal length which may bevaried in vivo to optimize the length there while obviating or mitigatedside branch occlusion.

[0084] Thus, the preferred form of the present endovascular prosthesisdevice is a stent system which comprises a longitudinally expansible orvariable portion. Preferably, the longitudinally expansible or variableportion is at least partially radially, covered by a non-porous or graftmaterial.

[0085] With reference to aortic dissection, the present prosthesisnormally will be implanted at the side of the intima tear in order toblock the flow from the true lumen into the false lumen at thedissection connection. The present prosthesis may be advantageously usedin optimizing the length of the prosthesis in treating dissection of thedescending part of the aorta.

[0086] A preferred feature of the present endovascular prosthesis isthat it has only a partial, radial non-porous or graft covering.Placement and positioning of the device can be facilitated byintravascular ultrasound and transesophageal echocardiography blockingthe tear and while obviating or mitigating covering the entire aorticwall—e.g., the portion of the aortic wall possibly containing importantside branches.

[0087] Once implanted, an advantage of the preferred form of the presentendovascular prosthesis is that it allows flow from the proximal to thedistal aorta even during the implantation of the device due to theunique design. In contrast, conventional stent grafts must be used withthe concurrent danger of abrupt rise of blood pressure leading to anextension and enlargement of the dissection.

[0088] The present endovascular prosthesis may be used advantageously toblock the tear, thereby obviating or mitigating flow from the true lumento the false lumen. Thus, the healing process begins which, in thesuccessful cases, will lead during follow-up within 6 months to totalobliteration of the false lumen and strengthening of the aortic wall. Inaddition the pressure in the false lumen is reduced or eliminated andthereby, the true luman can expand and improve the organ perfusion.

[0089] When properly deployed, the present endovascular prosthesis willprotect the diseased pant of the aorta, so that little or no blood isescapes from the lumen to the mediastinum and thereby, the patient isstabilized. Using intravascular ultrasound and transesophagealechocardiography., the present endovascular prosthesis may beappropriately navigated to block the damage of the aorta. Again as intreatment of aortic dissection, it is important to avoid blockage ofmultiple arteries which are supplying the back bone since this can leadto paraplegia with enormous consequences for the patient.

[0090] Indeed, to the knowledge of the present inventors, the presentendovascular device is the first such device to be useful in reliabletreatment of aortic diseases. Thus, with the present endovasculardevice, blockage of the aortic flow is obviated or mitigated and abruptblood pressure increases (which could lead to a fatal event) areavoided. Further, since the present device may be deployedendovascularly (i.e. non-surgically), it is generally safer for thepatient and is less of a burden on public health systems.

[0091] The present endovascular prosthesis may be used advantageously towrap the intimal flaps and thrombi to the aortic wall and therebyobviate or mitigate the danger of stroke and emboli without the need foranticoagulation. As the preferred form of the present prosthesis coversonly a radial portion of the aortic circumference, blocking of sidearteries, which are supplying the back bone, is obviated or mitigated.As the preferred form of the present prosthesis is open and not blockingthe flow from the proximal and distal aorta during the implantation, ablood pressure increase is obviated or mitigated. Thus, a uniqueadvantage of the present prosthesis is that it can be used even inmultiple places of the aorta when more parts of the aorta are showingthrombus formation.

BRIEF DESCRIPTION OF THE DRAWINGS

[0092] Embodiments of the present invention will be described withreference to the accompanying drawings, in which:

[0093]FIG. 1 illustrates a summary of the various categories of aorticdisease;

[0094]FIGS. 2a-2 e illustrate various categories of dissection of theaorta;

[0095]FIGS. 3a-3 b illustrates a perspective view of an expandableprosthesis in accordance with the present invention in its retracted andextended position;

[0096]FIGS. 4a-4 b illustrates a perspective view of an alternateembodiment of the present endovascular prosthesis in the retracted andextended position;

[0097] FIGS. 5-15 illustrate a sectional view of deployment of anembodiment of the present endovascular prosthesis in a lumen;

[0098]FIG. 16 illustrates a perspective view of a perfusion balloonuseful in the embodiment illustrated in FIGS. 5-16;

[0099]FIG. 17 is a sectional view taken along line XVI-XVI in FIG. 16,as used in a body passageway;

[0100] FIGS. 18-24 illustrate a sectional view of deployment of analternate embodiment of a present endovascular prosthesis; and

[0101]FIG. 25 illustrates a perspective view the endovascular prosthesisof FIGS. 18-24 after deployment.

BEST MODE FOR CARRYRNG OUT THE INVENTION

[0102] Thus, with reference to FIG. 3, there is illustrated anexpandable prosthesis 10 which comprises a plurality of annular members12 which are joined to one another by one or more longitudinal spines14. Annular members 12 are radially expandable. Further, spine 14 islongitudinally expandable.

[0103] Disposed over a portion of expandable prosthesis 10 is a covermaterial 16. Cover material 16 is adhered to various of annular members12.

[0104] In the longitudinally retracted version of endovascularprosthesis 10 (i.e. FIG. 3a), the longitudinal length of cover material16 is greater than the longitudinal length A of endovascular prosthesis10 over which it is disposed. This can be achieved by a suitable meanssuch as folding of cover material 10 and the like. Alternatively, covermaterials 16 can be made of a material which can stretch.

[0105] As shown in FIG. 3b, it is possible to lengthen endovascularprosthesis 10 prior to radio expansion thereof. The manner by which thisis achieved will be described hereinbelow. The point is, as the spacingbetween adjacent annular members 12 is increased, cover material 16unfolds or otherwise lengthens (e.g., by stretching) to allow thelongitudinal length B of cover material 16 to increase compared tolength A in FIG. 3a.

[0106] An alternate embodiment is illustrated in FIG. 4. Specifically,there is illustrated an endovascular prosthesis 10 a comprising a firstsection 11 and a second section 13. Sections 11 and 13 arelongitudinally movable with respect to each other (e.g., in atelescoping manner). Each of sections 11 and 13 are similarlyconstructed in that each comprises a series of annular members 12 awhich are interconnected by a longitudinal spine 14 a.

[0107] In the embodiment illustrated in FIG. 4, lengthening ofendovascular prosthesis 10 a is achieved by relative of extension ofsection 11 with respect to section 13. This enlarges the overall lengthof cover material 16 a which is disposed on each of sections 11 and 13.

[0108] As will be appreciated by those of skill in the art, thecombination of annular members 12 and 14 (FIG. 3) and sections 11 and 13(FIG. 4) may be any conventional stent design which is preferablyoptimized to facilitate navigation of the prosthesis to the target sitein the anatomy. The preferred design for the stent sections is thatdisclosed in the Penn et al. International patent applications referredto above. Of course, those of skill in the art will recognize that thepresent endovascular prosthesis is not restricted to the use of thespecific stent designs illustrated in FIGS. 3 and 4, and that anygenerally skill stent design may be used.

[0109] Preferably, cover material 16 (FIG. 3) and 16 a (FIG. 4) is asheet material such as Dacron™, Gortex™, other polymeric materials,bovine pericardium and the like. The nature of the material used forthis purpose is not particularly restricted. It is preferred that thematerial be substantially impermeable to bodily fluids, that it isgenerally biocompatible and that the physical nature thereof does notimpede delivery, deployment or general efficacy of the endovascularprosthesis after it has been implanted.

[0110] Cover material 16 (FIG. 3) and 16 a (FIG. 4) may also be derivedfrom a silicone-based material such as those commercially available fromNuSil Technology (Carpenteria, Calif.). A non-limiting example of suchmaterial is derived from a silicone-based dispersion commerciallyavailable from NuSil Technology under trade name MED-6640. This materialis usually obtained as a liquid dispersion in an organic insolvent suchas xylene. The dispersion may be used as such or the viscosity thereofbay he altered as desired by addition of further solvent.

[0111] Preferably, the cover material is attached to an otherwisetubular stent structure. The means by which attachment may be achievedis not particularly restricted. For example, the cover material could befixed to the appropriate spot on the stent using a suitable adhesive.Alternatively, the cover material could be sewn onto the stent. Those ofskill in the art will conceive of a number of other means by which thecover material may be fixed to the stent structure.

[0112] In another embodiment, cover material 16 (FIG. 3) and 16 a (FIG.4) may be made of the same material as the remainder of prosthesis 10(FIG. 3) and 10 a (FIG. 4) but preferably suitably modified to comprisesa number of slits, microcuts, slots, apertures or the like to reconcilethe feature of impeding bodily fluid (e.g., blood) therethrough with thefeature of rendering the cover material sufficiently flexible so as topermit delivery and deployment of the expandable prosthesis.

[0113] With reference FIGS. 5-16, a preferred mode of deployingendovascular prosthesis 10 a will be illustrated. For sake ofillustration only, various of the structural details of endovascularprosthesis 10 a discussed above are omitted from FIGS. 5-16. Further,for illustrative purposes only, endovascular prosthesis 10 a shown inFIGS. 5-16 is constructed from a plastically deformable material such asstainless steel, tantalum or the like.

[0114] Thus, with reference to FIG. 5, there is illustrated a lumen 100(this could be the ascending aorta referred to in FIG. 2 above) having ablockage 105 disposed on a wall thereof. In accordance with conventionalcatheterization techniques, initial steps (not illustrated for clarity)involve disposing a guidewire 110 in lumen 100 such that the distal endof guidewire 10 is distal blockage 105. Thereafter, a guiding catheter115 is disposed in a manner such that the distal end of guide catheter115 is proximal the distal extremity of blockage 105.

[0115] Thereafter, endovascular prosthesis 10 a disposed on a ballooncatheter 120, (or other suitable delivery system), preferably comprisingan elastomeric balloon at the distal end thereof, is extended fromguiding catheter 115 to expose distal portion of section 11 ofendovascular prosthesis 10 a.

[0116] Thereafter, a balloon 122 disposed on the distal end of ballooncatheter 120 is expanded in a conventional manner. This urges the distalend of section 11 of endovascular prosthesis 10 a against lumen 100 asshown in FIG. 6.

[0117] Next, balloon 122 is deflated and balloon catheter 120 isretracted such that balloon 122 is near the proximal end of section 13of endovascular prosthesis 10 a—this is shown in FIG. 7.

[0118] Thereafter, balloon 122 is partially expanded to urge theproximal end of section 13 of expandable prosthesis 10 a against theinside of guiding catheter 115—this is shown in FIG. 5.

[0119] Next, guiding catheter 115 is retracted as shown in FIG. 9. Sincethe proximal end of section 13 of endovascular prosthesis 10 a is urgedagainst the inside of guiding catheter 115 during this step, thiseffectively results in relative extension of section 13 from section 11of endovascular prosthesis 10 a.

[0120] Next, balloon 122 of balloon catheter 120 is deflated and ballooncatheter 120 is repositioned such that balloon 122 is near theoverlapping region of sections 11 and 13 of endovascular prosthesis 10a-see FIG. 10.

[0121] At this point, balloon 122 is expanded which results in urging ofsections 11 and 13 of endovascular prosthesis 10 a against lumen 100 asshown in FIG. 11.

[0122] Thereafter, guiding catheter 115 is retracted to expose theentire expandable prosthesis 10 a as shown in FIG. 12 and balloon 122 ofballoon catheter 120 is repositioned to expand the proximal end ofsection 13 against lumen 100.

[0123]FIGS. 13 and 14 illustrates successive expansion steps along thelength of endovascular prosthesis 10 a with the result that it is“remodeled” to occlude blockage 105.

[0124] Of course, while not specifically illustrated, it is preferredthat cover material 16 a (FIG. 4) is positioned such that it occludesblockage 105.

[0125]FIGS. 16 and 17 illustrate a preferred perfusion balloon which isuseful in the embodiment illustrated in FIGS. 5-15. The perfusionballoon is particularly useful to permit continued blood flow throughlumen 100 during “remodeling steps” illustrated in FIGS. 12-14.

[0126] With reference to FIGS. 8-24, deployment of an alternateembodiment of the present endovascular prosthesis will be described. Aswill be evident to those of skill in the art, FIGS. 18-24 illustratedeployment of an endovascular prosthesis in the ascending aorta of apatient. For clarity, the endovascular prosthesis is shown schematicallyas a series of hoops. Preferably, these hoops would be effectivelyinterconnected by a covering material such that the longitudinal lengthof the prosthesis is adjustable by an accordion-type movement. Further,the specific aortic disease being treated is not shown, again for thepurposes of clarity only.

[0127] Thus, a guidewire 200 is navigated endovascularly to a region ofthe ascending aorta 205 just proximal the patient's heart (not shown).Thereafter, a combination of a sheath 210, a balloon catheter 215 and anendovascular prosthesis 220 is delivered over guidewire 200 to ascendingaorta 205.

[0128] A balloon 225 disposed at the distal end of balloon catheter 215is expanded slightly so as to be urged against a pair of hoops 230 justproximal a distal hoop 235 of prosthesis 220. Next, the combination ofsheath 210 and balloon catheter 215 are retracted slightly in thedirection of the arrow shown in FIG. 19. This exposes distal hoop 235from sheath 210 resulting in self-expansion of distal hoop 235.Specifically, it is preferred that the hoops comprised in endovascularprosthesis 220 are constructed from a shape memory alloy such as Nitinolor the like.

[0129] With reference to FIGS. 19 and 20, balloon 225 of catheter 215 isdeflated, catheter 215 is retracted and balloon 225 is re-inflated so asto be urged against a pair of intermediately disposed hoops 240—see FIG.20 for the repositioning of balloon 225 of catheter 215.

[0130] Next, the combination of sheath 210 and balloon catheter 215 isretracted in the direction of the arrow shown in FIG. 20. This resultsin exposure of successive hoops of endovascular prosthesis 220 as shownin FIG. 21. As more hoops of endovascular prosthesis 220 are exposedfrom sheath 210, it may be desirable to reposition balloon 225 ofcatheter 215 as shown in FIG. 22. The repositioning of balloon 225 ofcatheter 215 may be achieved as described above with reference to FIGS.19 and 20.

[0131] Continued retraction of the combination of sheath 210 and ballooncatheter 215 results in further hoops of endovascular prosthesis 220being exposed from sheath 210 as shown in FIG. 22. With reference toFIG. 22, once the appropriate longitudinal length of endovascularprosthesis 220 has been reached, balloon 225 of catheter 215 is deflatedand the combination of sheath 210 and balloon catheter 215 is retractedas shown in FIG. 24 thereby exposing a pair of proximally disposed hoops245 of endovascular prosthesis 220. Thus, in the illustrated embodiment(FIG. 24), there is no substantial lengthening of the distance betweenproximally disposed hoops 245 of endovascular prosthesis 220. Thus,those who have skill in the art, will recognize that endovascularprosthesis 220 is particularly advantageous since the longitudinallength thereof mall be readily varied during implantation thereof in thepatient. This is particularly advantageous where the target anatomy ofthe patient is subject to varying dimensions on a patient-by-patientbasis. Further, the approach illustrated in FIGS. 18-24 is particularlyadvantageous since endovascular prosthesis 220 may be deployed whilemaintaining perfusion through the delivery system. Further, the presentendovascular prosthesis is advantageous since, during delivery thereof,undesirable stretching and related stress to the aorta is minimized oravoided. By avoiding such stretching of the aorta, placement of theprosthesis can be more easily reconciled with pre-procedure measurementswhich are taken to determine the appropriate length and size of thevessel.

[0132] The present endovascular prosthesis may further comprise acoating material thereon. The coating material may be disposedcontinuously or discontinuously on the surface of the prosthesis.Further, the coating may be disposed on the interior and/or the exteriorsurface(s) of the prosthesis. The coating material can be one or more ofa biologically inert material (e.g., to reduce the thrombogenicity ofthe prosthesis), a medicinal composition which leaches into the wall ofthe body passageway after implantation (e.g., to provide anticoagulantaction, to deliver a pharmaceutical to the body passageway and the like)and the like.

[0133] The present endovascular prosthesis is preferably provided with abiocompatible coating in order to minimize adverse interaction with thewalls of the body vessel and/or with the liquid, usually blood flowingthrough the vessel. The coating is preferably a polymeric material,which is generally provided by applying to the prosthesis a solution ordispersion of preformed polymer in a solvent and removing the solvent.Non-polymeric coating material may alternatively be used. Suitablecoating materials, for instance polymers, may be polytetraflouroethyleneor silicone rubbers, or polyurethanes which are known to bebiocompatible. Preferably, however, the polymer has zwitterionic pendantgroups, generally ammonium phosphate ester groups, for instancephosphoryl choline groups or analogues thereof. Examples of suitablepolymers are described in International Publication Numbers WO 93/16479and WO 93/15775. Polymers described in those specifications arehemo-compatible as well as generally biocompatible and, in addition, arelubricious. It is important to ensure that the surfaces of theprosthesis are completely coated in order to minimize unfavourableinteractions, for instance with blood, which might lead to thrombosis inthe parent vessel.

[0134] This good coating can be achieved by suitable selection ofcoating conditions, such as coating solution viscosity, coatingtechnique and/or solvent removal step.

[0135] While this invention has been described with reference toillustrative embodiments and examples, the description is not intendedto be construed in a limiting sense. Thus, various modifications of theillustrative embodiments, as well as other embodiments of the invention,will be apparent to persons skilled in the art upon reference to thisdescription. For example, those of skill in the art will appreciate thatit is possible to modify the specific embodiment illustrated in FIGS. 3and 4 such (i.e., a partially covered endovascular prosthesis) that theprosthesis is completely cover or completely uncovered. Further, in theevent the prosthesis is partially or completely covered, it is possibleto utilize a bioadhesive or the like to promote sealing engagement ofthe coveted portion of the prosthesis and the section of the bodypassageway against which it is urged. It is therefore contemplated thatthe appended clams still cover any such modifications or embodiments.

[0136] All publications, patents and patent applications referred toherein are incorporated by reference in their entirety to the sameextent as if each individual publication, patent or patent applicationwas specifically and individually indicated to be incorporated bagreference in its entirety.

What is claimed is:
 1. An endovascular prosthesis for implantation in abody passageway, the prosthesis comprising a tubular wall, the tubularwall being: (i) movable between a first longitudinal length and a secondlongitudinally length, and (ii) radially expandible for implantation ofthe prosthesis in the body passageway.
 2. The endovascular prosthesisdefined in claim 1, wherein the tubular wall comprises a first tubularwall and a second tubular wall in sliding engagement with one another.3. The endovascular prosthesis defined in claim 2, wherein the tubularwall comprises an annular portion for occlusion of a section of the bodypassageway, the annular portion comprising a first porous section and anon-porous section.
 4. The endovascular prosthesis defined in claim 3,wherein the tubular wall comprises a second porous section adjacent theannular portion.
 5. The endovascular prosthesis defined in claim 3,wherein the tubular wall comprises a third porous section adjacent theannular portion.
 6. The endovascular prosthesis defined in any one ofclaims 2-3, wherein the tubular wall comprises a second porous sectiondisposed adjacent one side of the annular portion and a third poroussection adjacent an opposed side of the annular portion.
 7. Theendovascular prosthesis defined in claim 6, wherein second poroussection and the third portion section are interconnected by the firstporous section.
 8. The endovascular prosthesis defined in any one ofclaims 3-7, wherein the non-porous section radially spans from about 90°to about 270° of the annular portion.
 9. The endovascular prosthesisdefined in an), one of claims 3-7, wherein the non-porous sectionradially spans from about 150° to about 250° of the annular portion. 10.The endovascular prosthesis defined in any one of claims 3-7, whereinthe non-porous section radially spans from about 180° to about 240° ofthe annular portion.
 11. The endovascular prosthesis defined in any oneof claims 3-10, wherein the non-porous section extends longitudinally adistance in the range of from about 2 cm about 10 cm.
 12. Theendovascular prosthesis defined in any one of claims 3-10, wherein thenon-porous section extends longitudinally a distance in the range offrom about 3 cm about 8 cm.
 13. The endovascular prosthesis defined inany one of claims 3-10, wherein the non-porous section extendslongitudinally a distance in the range of from about 3 cm about 6 cm.14. The endovascular prosthesis defined in any one of claims 3-13,wherein the non-porous section comprises a cover material disposed overa fourth porous section.
 15. The endovascular prosthesis defined in anyone of claims 3-14, wherein the non-porous section comprises a covermaterial disposed connected to the first porous section.
 16. Theendovascular prosthesis defined ill claim 15, wherein the cover materialcomprises a layer of polymer material.
 17. The endovascular prosthesisdefined in claim 1, wherein the tubular wall comprises a plurality ofinterconnected expandable annular members.
 18. The endovascularprosthesis defined in claim 17, wherein the annular members areinterconnected by a plurality of longitudinal members.
 19. Theendovascular prosthesis defined in claim 17, wherein the annular membersare interconnected by a cover material.
 20. The endovascular prosthesisdefined in any one of claims 1-19, wherein the tubular wall comprises atleast one radioopaque marker.
 21. The endovascular prosthesis defined inany one of claims 1-19, wherein the tubular wall comprises a pair ofradioopaque markers disposed at opposed ends of the tubular wall. 22.The endovascular prosthesis defined in any one of claims 1-19, whereinthe tubular wall comprises a pair of radioopaque markers disposed atopposed ends of the non-porous section.
 23. The endovascular prosthesisdefined in any one of claims 1-22, wherein the tubular wall isconstructed from a plastically deformable material.
 24. The endovascularprosthesis defined in claim 23, wherein the plastically deformablematerial comprises stainless steel.
 25. The endovascular prosthesisdefined in claim 23, wherein the plastically deformable materialcomprises a laminar structure.
 26. The endovascular prosthesis definedin claim 25, wherein the laminar structure comprises a layer ofplastically deformable, material and a layer of radioopaque material.27. The endovascular prosthesis defined in any one of claims 1-22,wherein the tubular wall is constructed from a self-expanding material.28. The endovascular prosthesis defined in claim 27, wherein theself-expanding material comprises a shape memory alloy.
 29. A method forendovascular blocking of an endovascular disease condition locatedbetween a first location point and a second location point in a targetbody passageway of a patient with the endovascular prosthesis defined inany one of claims 1-28, the method comprising the steps of: insertingthe prosthesis and a catheter within a body passageway bycatheterization of the body passageway; translating the prosthesis andcatheter to a target body passageway in which the endovascular diseasecondition is located; positioning the distal end of the prosthesis suchthe distal end of the prosthesis is substantially aligned with the firstlocation point; extending the distal end of the prosthesis with respectto the catheter; exerting a radially outward expansive force on thedistal end of the tubular wall such that the distal end of the tubularwall is urged against the target body passageway; fixing a proximalportion of the prosthesis with respect to the catheter; retracting thecatheter thereby longitudinally extending the expansible portion of thetubular wall until the proximal end of the prosthesis is substantiallyis substantially aligned with the second location point; freeing theprosthesis with respect to the catheter; retracting the catheter toexpose the proximal end of the endovascular prosthesis; and exerting aradially outward expansive force on the proximal end of the tubular wallsuch that the proximal end of the tubular wall is urged against thetarget body passageway.
 30. The method defined in claim 29, whereinaortic disease condition comprises aortic dissection.
 31. The methoddefined in claim 29, wherein aortic disease condition comprises bluntchest trauma.
 32. The method defined in claim 29, wherein aortic diseasecondition comprises aortic sclerosis.